The paper discusses the economic aspects of the most important questions (such as demand response or capacity allocation) related to differential pricing. First, we consider a revenue-neutral introduction of peak-load pricing. We examine under what circumstances does peak-load pricing lead to a Pareto improvement compared to uniform pricing. Second, we analyze what properties of customers make it profitable for a firm to introduce peak-load pricing. We find that on the supply side, incentives to introduce differential pricing may be technology-driven (i. e. high on-peak marginal costs) or demand-driven (i.e. low elasticity of substitution). Consumers benefit more if they can adopt to prices more flexibly. Innovative technology, such as smart meters, may help consumers benefit from real-time pricing. Such technology is expensive to install. This makes it necessary that consumers cover part of the costs. If they are myopic, or other effects of bounded rationality hinder their commitment, regulatory intervention might be needed to increase welfare. The more accessible enabling technology (price comparison websites, cheap smart meters etc.) will be, the more everyone will benefit from time-varying pricing.